Homobuffer thickness effect on the background electron carrier concentration of epitaxial ZnO thin films

Journal Article · Wed Sep 15 04:00:00 EDT 2010 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3486445· OSTI ID:21476479

Yang, Z; Zhou, H M; Li, L; Zhao, J Z; Liu, J L ^[1]; Chen, W V; Yu, P K. L. ^[2]

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1. Department of Electrical Engineering, Quantum Structures Laboratory, University of California, Riverside, California 92521 (United States)
2. Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

Epitaxial ZnO thin films were grown on r-plane sapphire substrates using plasma-assisted molecular-beam epitaxy. ZnO homobuffer layers grown at a lower temperature were introduced to improve the crystallinity of the top ZnO thin films. Thicker homobuffer layers lead to better crystallinity of the subsequent epitaxial ZnO thin films due to the strain relaxation effect. Residual background electron carrier concentration in these undoped ZnO thin films first decreases, then increases as the buffer layer thickness increases from {approx}1 to 30 nm, with a minimum electron concentration of {approx}1x10{sup 17} cm{sup -3} occurring in ZnO homobuffer of {approx}5 nm. These results demonstrate that the optimized ZnO homobuffer thickness to achieve both good ZnO crystallinity and low residual electron concentration is determined by the relative electron carrier concentration ratios and mobility ratios between the buffer and epi-ZnO layers.

• OSTI ID: 21476479
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 6 Vol. 108; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CHALCOGENIDES
CONCENTRATION RATIO
CORUNDUM
CRYSTAL GROWTH
CRYSTAL GROWTH METHODS
DIMENSIONLESS NUMBERS
ELECTRON DENSITY
ELECTRON MOBILITY
EPITAXY
FILMS
LAYERS
MATERIALS
MINERALS
MOBILITY
MOLECULAR BEAM EPITAXY
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PARTICLE MOBILITY
PLASMA
PROCESSING
RELAXATION
RESIDUAL STRESSES
SAPPHIRE
SEMICONDUCTOR MATERIALS
STRAINS
STRESSES
SUBSTRATES
THIN FILMS
ZINC COMPOUNDS
ZINC OXIDES